This invention relates to stearoyl lactylate salt compositions, and method of production thereof, which compositions are surprisingly low in hygroscopicity and relatively high in softening and melting points. More particularly, this invention relates to thermally mixed compositions comprising from about 70% to about 98% by weight of stearoyl lactylate salts, especially stearoyl-2-lactylate salts, and from about 2% to about 30% by weight of stearin.
Stearoyl lactylate salts have been sold in commerce for many years, being used especially, in the edible forms, as additives in bakery products to improve quality. Sodium and calcium stearoyl-2-lactylates are the most common and commercially used of the salts and their addition to products for human consumption is controlled by the U.S. Food and Drug Administration as set forth in Food Additive Regulation 21 CFR Section 172.846 and 172.844 respectively, and also in 21 CFR Section 136.110, in particular subsection C-15.
As used herewithin, the terms sodium and calcium stearoyl lactylate refer to both the laboratory produced and commercial grades of each stearoyl lactylate salt. The commercial grade stearoyl lactylate salts, while controlled in food products as described above, actually encompass a variety of lactylates including those having a wide range of lactyl groups and various fatty acids taken from the acyl group. For example, the stearoyl lactylate salts are generally written as sodium stearoyl-m-lactylate and calcium stearoyl-n-lactylate wherein m and n represent the average number of lactyl groups (polylactyls) present, that is, each m and n represents an average of a range which may extend from 0 to 11 when used as baking additives. Lactylates having 1 to 3 lactyl groups are considered most functional in baking with an average of 2 preferred. In normal nomenclature each m and n is rounded to the nearest whole number, hence, 2 may actually represent a range of 1.51 to 2.50. As used herein a non-decimaled number, such as 2, references a range whereas a decimaled number, such as 2.0 references a specific average number. In addition, commercial grade stearoyl lactyls may contain a wide range of acyl fatty acid radicals, including those of C.sub.14 to C.sub.22 fatty acids, the most common of which are C.sub.18 and C.sub.16 fatty acids. Thus, for example, a particular stearoyl lactylate may be made from stearin fatty acid containing 50% stearic acid and 50% palmetic acid. Therefore as used herein, stearoyl lactylate salts are understood to include as used herein, stearoyl lactylate salts are understood to include the wide range of lactyl groups and various fatty acids substitutions for stearic acid which may be present in commercial stearoyl lactylate salts.
Although the sodium and calcium stearoyl lactylates are the most common of the stearoyl lactylate salts, salts of other metals may be produced according to the present invention, especially stearoyl lactylate salts of the alkali and alkaline earth metals. One example of such a salt is potassium stearoyl lactylate, which is non-toxic and may be produced according to the present invention, but which is not presently approved for use as a food additive.
Conventional methods of manufacture of sodium and calcium stearoyl lactylate salts are well known and an example of such is given in Tsen et al. U.S. Pat. No. 3,883,669.
The conventional stearoyl lactylate salts are characterized by their relatively low softening and melting points and are normally highly hygroscopic, particularly the sodium salt, which will be shown below. Such salts are often used, especially in the baking industry, as powders such that 100% of the powder will pass through U.S. 40 mesh screen. The low melt and high hygroscopicity characteristics of such compositions present serious storage and warehousing problems, particularly in summer months because of the tendency for the powdered materials to coalesce into lumps and hard cakes. Storage costs are increased because of special care required, and if the salts do become caked they normally can no longer be used and must be either scrapped or returned to the manufacturer for additional processing. The manufacturers of such salts thus suffer from poor customer relations generated by such caking.
Therefore, the principal objects of the present invention are: to provide stearoyl lactylate salt compositions which have higher melting and softening points than conventional stearoyl lactylate salts; to provide such stearoyl lactylate salt compositions which are less hygroscopic than conventional stearoyl lactylate salts; to provide a method for manufacture of higher melting and lower hygroscopic stearoyl lactylate salts; and to provide such stearoyl lactylate salt compositions which are convenient to handle, economical to use and particularly well suited for their proposed use.
Other objects and advantages of this invention will become apparent from the following description wherein is set forth by way of example, certain embodiments of this invention.
As required, detailed embodiments and examples of the present invention are disclosed herein. However, it is to be understood that the disclosed embodiments and examples are merely exemplary of the invention which may be embodied in many various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention.
The present invention is based on the unique and surprising discovery that the thermal mixing of hydrogenated stearin with stearoyl lactylate salts advantageously increases the melting and softening points and reduces the hygroscopicity of such salts beyond what would be expected.
As used herein the term stearin refers to fully hydrogenated fats and oils, that is such stearin having an iodine value of less than 7, wherein a minimum of 50% of fatty acid radicals thereon (by weight of fatty acid) is C.sub.18 fatty acid. This terminology generally agrees with commercial practice. It is understood that the term fat refers to triglycerides which are solid or semisolid at normal ambient temperatures and oil refers to triglycerides which are liquid at such temperatures. Thus, as used herein, stearin may include a wide variety of triglycerides whose individual fatty acids may range from C.sub.12 to C.sub.24, the most common (besides C.sub.18 stearic acid) being C.sub.16 palmetic acid. It is also understood that stearin may include amounts of free fatty acid as are found in commercial grades thereof. It has been found that the most functional stearin for the present invention are those having high percentages of C.sub.18 stearic acid. Thus hydrogenated soybean oil stearin, having fatty acids which are in the nature of 90% (by weight of fatty acid) C.sub.18 stearic acid is very functional. Many other vegetable and animal oil stearins (such as those of corn oil, cottonseed oil, herring oil, lard, olive oil, palm oil, peanut oil, rapeseed oil, safflower oil, sardine oil, sunflower oil, tallow, or mixtures thereof) are also functional, however, as the percentage of less than C.sub.18 fatty acids increases, functionality decreases. Herring oil, rapeseed oil, and sardine oil have more than 50% of at least C.sub.18 fatty acid and are composed of fatty acids of which a majority are greater than C.sub.18 in length. Hence fully saturated animal tallow having about 50% C.sub.18 stearic fatty acid and 50% C.sub.16 palmetic fatty acid is less functional than soybean oil stearin. For stearoyl lactylate salts used in food products, edible stearins are utilized, however, the non-edible stearins are also functional in the practice of the present invention.
The term thermal mixing as used herein refers to addition of the stearin to the stearol lactylate salt formulation at temperatures above ambient, and preferably while the stearoyl lactylate salt is in a molten state. The stearin may be thermally mixed during any or all of the conventional process steps of manufacture of stearoyl lactylate salts; while such salts are still molten as described, after the completion of the salt while still molten from manufacture, or added to such salts which have been remelted into the molten state. It appears preferential to add the stearin in the first step of production of such salts, wherein the stearic acid and lactylic acid are mixed and an esterification reaction occurs between the acids, as the stearin helps control foaming, thereby facilitating manufacture.
The term co-melted as used herein when referring to stearin addition is understood to mean that the previously manufactured and cooled lactylate salt is remelted, and during or after such remelting, while still in a molten state, the stearin is added and mixed therewith. Also as used herein the term thermally co-mixed when used in reference to stearin is understood to mean that the stearin is added to and mixed with the lactylate salt during production of same while the lactylate salt is still in a molten state resulting from production and before cooling.